I don't think all the legal speculation here is very helpful. I'm sure the Board or someone else will sagely advise us that the board is self-governing and self-perpetuating and no other legal authority is necessary.
In any case, its irritating to see people providing cover for the Board's lack of transparency or failure to be forthcoming in a timely manner. Why not let them make their own excuses? If indeed there is some confidentiality issue, let them argue that the Wikimedia community should be satisfied with never knowing the salient details.